1.Preheat oven to 180°C. Line 15 holes of two 12-hole muffin pans with paper cases.
2.Beat butter, eggs, milk, sugar and sifted dry ingredients in a medium bowl with electric mixer on low speed until ingredients are combined. Increase speed to medium; beat until mixture is smooth and has changed to a paler colour. Drop ¼ cups of mixture into paper cases.
3.Bake about 20 minutes. Stand cakes in pans 5 minutes before turning, top-side up, onto wire racks to cool.
4.To make dark chocolate ganache, bring cream to the boil in small saucepan; remove from heat. When bubbles subside, stir in chocolate until smooth. Cool 15 minutes.
5.Spread cold cakes with an even layer of ganache. Place a snowball on top of each cake.